Exhaust gases produced during combustion of fuel in a combustion chamber of an internal combustion engine generate highly elevated temperatures, temperature nonuniformities and heat fluxes in the combustion chamber, which lead to thermal stress of the combustion surface of the combustion chamber and a reduction or deterioration of mechanical properties of the combustion chamber surface. Thermal stress may result from expansion and contraction of the combustion chamber surface and adjacent material resulting from changes in temperature in the combustion chamber and cooling passages in the cylinder head and thermal conduction through the cylinder head body. Thermal stress from the combustion pressure escalates mechanical loading on the combustion chamber, and may result in cracking. Limiting combustion temperatures to decrease thermal stressing of the combustion chamber can limit the efficiency of the combustion event and thereby limit the fuel economy which may otherwise be achieved by the engine.